What is Custom Metadata?
Custom Metadata is Salesforce’s way to store an app’s settings as metadata rather than as data, so the settings move between orgs in a change set or a deployment, the way code does.
In Salesforce
A Custom Metadata type is defined much like a custom object, but its records are metadata. An admin creates them in Setup › Custom Metadata Types › Manage Records, adds them to an outbound change set under Custom Metadata Type records, or deploys them with the rest of a project kept in source control. Settings kept as ordinary data records have to be exported from one org and loaded into the next.
How Rowhouse handles it
Every Rowhouse grid is Custom Metadata: seven types, from the Grid Configuration that defines a grid to its columns, display rules, filters, actions and child tables, plus one Rowhouse Setting for the package as a whole. Admins build them on the Grid Admin tab or in Setup. No configuration records ship with Rowhouse, and every setting an admin edits belongs to your org, so an upgrade has nothing of yours to overwrite.
An example
An account directory is one Grid Configuration record, holding the object, the sort and what users may do, and one Grid Column record per column, each pointing back to it by name. To move it from a sandbox to production, an admin adds the configuration and every record that points to it to one outbound change set, together, with the Lightning page the grid sits on. A grid with child tables also needs its child grids in the target org.
Related terms
Custom Metadata: questions
Why does it matter that grid settings are metadata?
Because grids then follow the same release path as the rest of your org: build and test a grid in a sandbox, move it to production in a change set, and keep it in source control. Nobody re-creates a grid by hand in each org.
What happens to my grids if Rowhouse is uninstalled?
Before the package can be uninstalled, its Custom Metadata records — your grids — must be deleted, as with any package whose configuration lives in Custom Metadata. Only Setup can delete Custom Metadata records, and deleted records cannot be restored.
Three things you can verify without asking us
Free. Not freemium, not a trial, not a tier.
Install it, assign the permission sets, build your first grid on the Grid Admin tab. Everything else is in the Grid Guide inside the app.